I used fondant this winter instead of the usual sugar bags, the results have not been great with the bees hardly touching it.
Lost one hive to isolation starving although they had a block of fondant 10mm above the cluster, they had eaten a little of it but not enough to keep them going, although it was well wrapped it appears to have dried out.
I had 2 nucs with Perspex covers where I had been judging their needs by the depletion of the fondant, but when I opened them they had few stores but again had hardly touched the fondant.
Judging by the success of others using this for winter feed I'm obviously missing something